Although the pen is an important tool of our daily life nowadays, the pen having only a single function is very hard to attract the consumer. Currently a new kind of light pen is found in the market. The new light pen has a light source set up at the tail end of the pen holder to illuminate throughout the pen nib via the guidance of the pen holder to facilitate the reading for the consumer under the dusky condition. But when it comes to read the writing on the paper with different colors and if the color of the light source happens to be in the same color code of the color of the paper, the writing becomes not legible. What is more, the pen is always taken along with us but not the flashlight, therefore, it would be very convenient for us if the function of illumination can be added to the pen, for instance, when it comes to search for articles or search the key hole for opening the door in the dark, the pen taken along with us and having the light source can be functioned as a mini-flashlight to overcome this kind of difficulty.